**5.1 Nano-biopesticides**

Nano-biopesticides are attractive due to their tiny size, high surface-area-tovolume ratio, stability, enhanced efficacy, better solubility, mobility, and decreased toxicity. Nano-biopesticides are also suggested because of their low toxicity (see **Figure 1**). Chemical pesticides are directly applied to plants can possess toxins released by air into the food chain and cause environmental issues. To control these issues, pesticides with formulations of nano-particles such as micelles and nanocomposites reduce the chances of both environmental and health issues. Similarly, clay-based nanotubes deliver pesticides to control pests [75].

Like nano-fertilizers, nano-biopesticides are contained in carriers that enable for regulated release of active ingredients to accomplish desired effects in a given environment. Stiffness and penetrability are two properties enhanced by adding nano-biopesticides to biopolymers. Crystallinity, thermal stability, solubility, and

#### **Figure 1.**

*The importance of nanotechnology for the formulation of nano-based biopesticides. This figure is reproduced from Lade et al. [74].*

biodegradability are also enhanced [76, 77]. When nanomaterials were applied to the soils, nano-biopesticides containing nanomaterials resulted in the growth of mutualistic microorganisms that promote the pants' activities [17]. Sometimes, toxicity can be induced by coatings of silver-based nano-particles that could be reversed by biocompatible coatings, thus increasing the chances of seed germination in plants. Recently, nano-emulsions, nano-encapsulates, nanocontainers, and nano-cages have been reported as some nano-pesticide delivery techniques with different functionalities for plant protection [77].

Further research shows that cationic polymers may bind to polyanionic surfaces of bacteria, disrupt cell membranes, and kill pests. In agriculture, plants may be treated with biopesticides, such as nano-biopesticides, which can decrease microbial resistance, whereas chemicals applied directly to plants are unable to suppress a wide range of bacterial growth. Tertiary ammonium groups may be found in nano-particles as lengthy amino acid chains. Depending on their structure, these groups may attack various pests and illnesses, including bacteria. Because of their high activity in a wide variety of environmental and chemical conditions, polymers with quaternary ammonium groups in their chains are widely used [78]. Many polymers with this characteristic have been found and researched throughout time. For example, amphiphilic copolymers, functionalized cationic polycarbonates, poly(amidoamines), polyethylenimine, poly(methyl methacrylates), amino celluloses and chlorinated cellulose acetates are now available [78–80].

Essential oils (EOs) are highly volatile secondary metabolites found in many higher plants and flowers and certain fruits and vegetables. In addition to their traditional uses in medicine and cosmetics, a new study indicates they represent a major natural source of ecologically friendly pesticides. Essential oils are often used to treat gardening pants to keep insects and bees out of the garden. Invertebrates become neurotoxic when their nervous systems are suppressed of GABA and acetylcholine esterase (ACE) [81]. This 2007 research evaluated the anti-pest effects of plant extracts, essential oils, their purified components, and plant-based nanoformulations, as well as their modes of action. Temperature, light, and oxygen supply all have an impact on the EO's integrity. Researchers found that encapsulating flaxseed in gelatin and Arabic capsules may improve effectiveness by up to 84 percent, preventing the production of certain oxidants that stimulate the growth of some insects [82]. Sagiri *et al.* [83] summarized many techniques for encapsulating vegetable oils, including associated production processes, antimicrobial applications, insecticide/pesticide/pest repellant formulations, and antimicrobial applications. Purslane mustard, according to the manufacturer, is efficient against Sitophilus granaries and other grain-feeding insects. Using nanotechnology to control weevils and other pests improved their efficiency by about 7%, 21%, and 98%, according to prior research [84].

A variety of plants with nano-emulsions of ECs can be used to control the larval infections of different insects. These plants are *Tagetes minuta, Ageratum conyzoides* and *Achillea fragrantissima* used to control the growth of *Callosobruchus maculatus*. These nano-emulsions can be applied to kill or inhibit the growth of eggs and larvae in the form of fumes with treatment ranges from 16.1–40.5 μL/L air and 4.5–243 μL/L air, respectively [85]. The encapsulation of EOs can be performed through the use of nano-particles composed of liposomes and solid lipids. Encapsulation of EOs can be carried out through inverse gelation and oil emulsion [86]. Encapsulation of EOs through liposomes is helpful against microbes by protecting the cell membrane from the effects of EOs [87]. However, different types of nano-particles are used for pest management. Microparticles are also used to stabilize the effects of EOs. The encapsulation of carvacrol was performed with

#### *Nano-Biopesticides as an Emerging Technology for Pest Management DOI: http://dx.doi.org/10.5772/intechopen.101285*

a diameter of 0.5 μm with the cell wall of *Saccharomyces cerevisiae* to control the larvae of *Rhipicephalus microplus* and LC50 formulations of about 0.71 mg/mL. The cell wall of *Saccharomyces cerevisiae* appears more helpful in maintaining the low volatility of encapsulated carvacrol that maintains the acaricidal activity up to 60 hours [88].
